The invention relates to devices for holding wafer-shaped articles, such as semiconductor wafers.
Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668.
The patents referenced above operate on the Bernoulli principle, such that the wafer receives subjacent support from a gas cushion rather than by contact with the chuck. Such chucks nevertheless ordinarily include a circular series of pins that are positioned radially outwardly of a wafer positioned on the chuck. Those pins prevent lateral displacement of the wafer relative to the chuck.
Other spin chucks operate under control of magnetic fields, by fashioning the chuck body as a magnetic rotor positioned coaxially within a surrounding annular magnetic stator, as described for example in U.S. Pat. No. 6,485,531. In such chucks the magnetic rotor supports the wafer. Commonly-owned co-pending application U.S. Pub. No. 2012/0018940 describes magnetic rotor designs that better withstand the often extreme temperatures to which such chucks are exposed in use. However, the present inventors have discovered that there remains a need for improved chuck designs that are less adversely influenced by higher temperature use conditions.